Electrical conductor connections



July 5, 1966 R. E. PARRlLLl ELECTRICAL CONDUCTOR CONNECTIONS 2 Sheets-Sheet 1 Filed Jan. 2, 1964 FIG. 3

FIG?

RALPH E. PARRILLI INVENTOR ATTORNEY July 5, 1966 R. E. PARRILLI ELECTRICAL CONDUCTOR CONNECTIONS 2 Sheets-Sheet 2 Filed Jan. 2, 1964 FIG. 6

RALPH E. PARRILL! INVENTOR.

mmm LU.

ATTORNEY material fuses into adjacent uninsulated conductors.

United States Patent 3,259,685 ELECTRICAL CONDUCTOR CONNECTIONS Ralph E. Parrilli, Paterson, N..l., assignor to General Precision, Inc., Little Falls, N..l., a corporation of Delaware Filed Jan. 2, 1964, Ser. No. 335,198 Claims. (Cl. 174-685) The present invention relates to a method and apparatus for connecting a pair of electrical conductors, and more particularly to a method and apparatus for connecting each conductor of a first high-packing density conductor matrix to a respective conductor of a second highpacking density conductor matrix.

' The invention is particularly useful in connection with electroluminescent display panels, as-described in US. patent application Serial No. 43,410, filed July 18, 1960, which is now US. Patent No. 3,136,912, and which is assigned to the same assignee as this application! A conventional type of electrical connection between the ends of two electrical conductors cannot be made easily and effectively when connecting respective conductors of the type found in two-high-packing density conductor matrices. In the construction of present-day, high resolution electroluminescent display panels, it is necessary to make reliable electrical connections between individual conductors of two respective groups having 200-4000 conductors abreast. A typical panel of this type which has, for example, a density of 500 conductors per inch, and in which each conductor has an outside diameter of about 0.001 inch or 1 mil thickness, would have a spacing between the outer surfaces of adjacentconductors which is equal to about 0.001 inch, or 1 mil width. Obviously, with such close spacing, conventional connection of the type where the ends of a pair of conductors are wrapped or tied together are not suitable. In addition, with such close spacing, a solder or weld type of connection, either where the two conductors are lapped or butted, is not suitable because the connecting In attempting to overcome, this problem, it has been the practice to spread-out, or fan-out, the-adjacent conductors .in both groups to a very large extent (i.e., more than twice the normal Width of the group) to obtain sufficient space transversely between adjacent parallel conductor wires to permit the use of conventional joints electrically isolated from one another. Therefore, such attempts FIGURE 5 is a perspective view of an electrical connection in accordance with the invention; and

FIGURE 6 is a plan view of an electroluminescent display panel in modified form.

Referring to FIGURES 1-5, one embodiment of the present invention is an electrical connection 10 comprising an electrically-conductive transparent filament 12 connected to an insulated-wire conductor 14. Filament 12 has an end portion 16 making said connection with conductor 14.

Conductor 14 is comprised of an electrically-conductive metallic wire 20 having an outside diameter or thickness which is preferably larger than the thickness of conductive filament 12, and an insulating sheath 18, composed of etch-resistant dielectric insulating material for encasing conductor 14. Conductor 14 has a finite end segment 22 which has a specific shape as will be described hereafter. Insulating sheath 18 has an inside diameter which is preferably larger than the outside diameter of filament 12. Sheath 18 encases wire 20 over its entire length except for a segment portion 22 exposed by a cut-out in the end of the sheath as hereinafter described. Conductor 14 is preferably positioned on a glass substrate 23, or the like, during the manufacture of connection 10. Substrate 23, having an edge 21, is shown in FIGURES l-4 for ease of illustrating the connection 10. Electrical connection 10 in its preferred form is best illustrated by FIGURE 5.

The cut-out in sheath 18 is defined by the edges 24, 26, 28 of the remaining end portion 34. The length of the sheath cut-out portion 34 is approximately equal to the length of conductor segment 22. Sheath 18 hasa thickness 30 which is preferably constant, peripherally and longitudinally .of conductor 14. Sheath 18 has an end face 32, which is preferably substantially at right angles to the longitudinal dimension of conductor 14.

The segment 22 of wire 20 has a reduced and altered cross-section as compared to the cross-section over the have not been satisfactory because the transverse width at the fanned-out line of connections of a typical pair ofsuch connecting conductor panels, relative to the normal width of each such panel away from said line of connections, would become excessive in most assemblies. Accordingly, it is one object of the invention to minimize the transverse spacing necessary between connecthroughout the several views, and wherein:

FIGURE '1 is a side elevation of an end portion of an insulated wire conductor;

FIGURE 2 is a sectional view as taken on line22 of FIGURE 1;

FIGURE 3 is a sectional view similar to FIGURE 2; 7 FIGURE 4 is another sectional view similar to FIG- URE 2;

has a length which preferably is not greater than the length of cut-out edges 24, 26 and a uniform cross-section.

As shown in FIGURES 3 and 5, the cross-section of wire segment 22 is substantially smaller than that of sheath cut-out portion 34. Recess 38 serves to position filament 12 during its assembly to conductor 14. In constructions where conductor 14 has a size in the order of 0.002 inchor 2 mil thickness, and filament 12 has a size in the order of about 0.001 inch or 1 mil thickness, such a recess 38 in conductor 14 is very useful in positioning filament 12. Even with the aid of a laboratory type microscope, it is diflicult to see and handle a conductor 14 and filament 12 of this type, so that recess 38 avoids the need for special fixtures to position and align filament 12 with conductor 14 in the making of an electrical connection 10 therebetween.

Conductor 14 and filament 12 are joined together as a structural unity, preferably by a suitable adhesive 40 or the like. Recess 38 serves to retain adhesives applied in a liquid state until hardening takes place. The recess walls or sheath thicknesses 30 surround and thus insulate the adhesive-coated joint between filament 12 and conductor 14. Consequently, a plurality of conductors 14 can have a planar, side-by-side arrangement, without transverse clearances or gaps therebetween; and such conductors 14 with such arrangement, can 'be connected respectively to a plurality of filaments 12 in end-to-end, overlapping connection, with each connection 10 and its respective adhesive 40 being insulated from each adjacent connection.

Adhesive 40 is preferably composed of an electricallycon-ductive material, and is bonded to the adjoining surfaces of conductor 14 and filament 12, as best illustrated in FIGURE 4, to make a sound electrical connection 10. However, a non-conductive .adhesive can be used between the contiguous surfaces of filament 12 and wire segment 22 and/ or the inner surface of cut-out sheath portion 34, simply to establish electrical contact between the wire and filament.

The preferred method of manufacture of electrical connection 10, includes the steps of: first, forming the cut-out in insulating sheath 18 along end segment 22 of wire conductor 14 to expose metallic wire core 20; second, contacting the end segment 22 of wire conductor 14 with an etching solution to form recess 38, etching solution being inactive with the material of sheath 18; third, overlapping the end portion of filament 12 and the etched portion of metallic wire 20 within recess 38; and, fourth,

bonding the lapped portions of filament 12 and conductor 14.

The first manufacturing step, i.e., forming the cut-out in sheath 18, is-preferably accomplished by abrasion. Specifically, a suitable abrading tool is brought into engagement with the upper surface of wire conductor 14 along its end segment and an arcuate section of the insulation is worn away. customarily, and advantageously,

this is accompanied by removal-of the arcuate segment of wire 20 subtended by the abraded sheath portion.

The second manufacturing step involves contacting end segment 22 of conductor 14 with an etching solution which is active upon the metal of wire 20 but inert with respect to the material of sheath 18. Conveniently, this is accomplished by immersion of at least the extreme end of segment 22 in the etching solution until the exposed surface of metallic wire 20 is etched away to a point below the unremoved peripheral portion of sheath 18, thereby forming recess 38.

After completion of the etching step, followed by rinsing if necessary, the end portion of conductive filament 12 is inserted into recess 38 and laid against the etched surface of the metallic wire 20 to form a lap joint. This joint is then securedby the application of suitable conductive adhesives within recess 38 or by a combination of conductive and non-conductive bonding agents as previously explained in connection with the description of the resulting connection. A wide variety of materials are commercially available for this purpose including airdrying silver paints, conductive and non-conductive epoxy resins, and the like.

' When joining groups of closely-spaced conductors, care should be exercised in the application of conductive materials to avoid shorting between adjacent conductors. The entire region of the completed joint preferably is potted by the application of a layer of epoxy or the like.

An electroluminescent X-Y coordinate display panel 42 embodying the present invention is illustrated in FIG- URE 6. As is well-known in the art, electroluminescent display panels such as panel 42 may consist of a pair of superposed matrices of conductive glass filaments arranged to form a grid. The glass filaments are of extremely small diameter and closely spaced so that it is possible for such a matrix to have a resolution of 500 lines per inch. Each glass filament must be connected to a respective input lead and a layer of electroluminescent phosphor is interposed between the matrices. Thus, an input to one filament of each of the matrices activates 'the phosphor at the point of their intersection. For additional information regarding electroluminescent display panels and methods of their fabrication reference may be had to the aforementioned U.S. patent application Serial No. 43,410, now US. Patent No. 3,136,912. The panel shown in FIGURE 6 is bonded to a transparent substrate 23 as is the usual custom. The lead-in filaments of only one of the matrices are shown and designated collectively by reference numeral 44. These are spread out or fanned somewhat in order to match the spacing of the signal input matrix 46 which is somewhat greater due to larger wire size and/or the presence of insulation .sheath 18. The leads 19th; other matrix of the panel 4% have been omitted as if trimmed off at the edge of the panel for ease of illustration. It will be understood that in the panel the conductive glass filaments alternate with non-conductive glass filaments which are interposed to isolate the conductive filaments from one another.

Supply conductor matrix 46 is made up of a plurality of closely-spaced fine wire conductors joined to a respective one of the glass filaments 44 in the manner hereinbefore described with reference to FIGURES 1-5.

While the present invention has been described in a preferred embodiment, it will be obvious to those skilled in the art from the precedingspecification that various modifications can be made therein within the scope of the invention; for example, instead of making the cutout in the insulation sheath and recess 38 of uniform cross-section, the end of conductor 14 can be initially abraded at an angle so as to produce a tapered cut-out and wire end segment 22. Moreover, the electricalconnection between the lap filaments can be accomplished by means of electrically or chemically deposited coatings with a bonding agent applied subsequently to achieve the requisite mechanical strength in the bond. In view of the numerous possible modifications and variations that may be made without departing from the invention, it is aimed .to cover in the appended claims all such changes and modifications as fall within the true spirit and scop of the invention.

What is claimed-is:

1. An electrical connection between conductors, comprising: I

a length of electrically-conductive wire;

a sheath of dielectric insulation encasing said wire over its entire lengthexcept for a finite segment adjacent one end thereof;

said sheath having a cut-out extending the length of said segment, the transverse dimension of the cut-out being substantially less than half the peripheral dimension of the sheath, at least at one end of said segment;

the wire constituting said segment having a reduced and altered cross-section including a substantially fiat surface exposed through said cut-out;

at least an extreme end portion of said wire segment having a smaller cross-section than the corresponding area enclosed by said sheath; and

a conductor of substantially smaller cross-section than said wire, having one'end making a lap joint with, and electrically bonded to said surface of said wire.

2. An electrical connection as claimed in claim 1 and in which said conductor of smaller cross-section isan electrically-conductive glass filament.

3. A plurality of electrical connections between two conductor panels, comprising:

a first panel with conductors having a plurality of lengths of electrically-conductive wires with adjacent end segments;

said first-panel conductors having dielectric insulation encasing each said wire over its entire length except for a finite segment adjacent one end of each wire;

said dielectric insulation having a plurality of cut-outs with one cut-out adjacent the end segment of each said wire, and each said cut-out extending the length of its respective end segment and having a transverse dimension which is substantially less than half the peripheral dimension of its respective wire, at least atone end of said segment;

each said wire having a reduced and altered cross-section along its end segment including a surface exposed through its cut-out;

at least an extreme end portion of said segment in each said wire having a smaller cross-section than its corresponding area enclosed by said insulation; and

a second panel having a plurality of filaments of substantially smaller cross-section than said first-panel conductors, each filament of said second panel hav- 5 6 ing one end overlapping and electrically bonded to end portion received within said conductor recess the surface of a respective conductor wire of said first and overlapping said wire-core end segment; and panel. s means composed of electrically-conductive material and 4. An electrical connection between conductors, com disposed within said recess and engaging said overprising: 5 lapping portions of said filament and insulated-wire a length of insulated-wire conductor with an end face conductor for making an electrically-conductive lap and a longitudinal axis having an electrically-conjoint therebetween. ductive metallic wire core with a finite segment of 5. An electrical connection as claimed in claim 4 and reduced cross-section adjacent one end thereof and in which said wire-core end segment within said recess an insulatin sheath of etch-resistant dielectric t 10 has a cross-sectional thickness and area which is smaller rial covering said wire core; than the corresponding cross-sectional thicknesses and said conductor end face having a recess having a, depth areas of said wire-core portions longitudinally displaced extending substantially parallel to said conductor m Said recessaXis and having opposite sidewalls formed by portions of said insulating sheath material and being open '15 No references cited.

on its radially outer side and having a radially inner sidewall which is formed at least in part by said LARAMIE E. ASKIN, Primary Examiner.

end segment of said wire core; a length of electrically-conductive filament having an DARRELL CLAY Examiner 

4. AN ELECTRICAL CONNECTION BETWEEN CONDUCTORS, COMPRISING: A LENGTH OF INSULATED-WIRE CONDUCTOR WITH AN END FACE AND A LONGITUDINAL AXIS HAVING AN ELECTRICALLY CONDUCTIVE METALLIC WIRE CORE WITH A FINITE SEGMENT OF REDUCED CROSS-SECTION ADJACENT ONE END THEREOF AND AN INSULATING SHEATH OF ETCH-RESISTANT DIELECTRIC MATERAIL COVERING SAID WIRE CORE; SAID CONDUCTOR END FACE HAVING A RECESS HAVING A DEPTH EXTENDING SUBSTANTIALLY PARALLEL TO SAID CONDUCTOR AXIS AND HAVING OPPOSITE SIDEWALLS FORMED BY PORTIONS OF SAID INSULATING SHEATH MATERIAL AND BEING OPEN ON ITS RADIALLY OUTER SIDE AND HAVING A RADIALLY INNER 